Polyolefin resins which are widely used as general purpose resins are excellent in heat resistance, solvent resistance and dielectric characteristics. After further improving the heat resistance, rigidity, dimension stability, impact resistance, etc. of the polyolefin resins having such excellent characteristics, the present inventors once proposed novel Cycloolefin random copolymers (for example, in Japanese Patent L-O-P Nos. 168708/1985 and 120816/1986) having alicyclic structures, and prepared from ethylene and bulky cycloolefins. The inventors further proposed a method for blending the cycloolefin random copolymers with specific polymers (for example, Japanese: Patent L-O-P Nos. 163236/1989 and 163241/1989) to improve the impact resistance of the cycloolefin random copolymers. Though these resin compositions have excellent characteristics under ordinary using conditions, the resin compositions tend to be oxidized under severe conditions at alicyclic structures, that is, the constituent units derived from cycloolefins, because the main component of the resin compositions is an olefin resin having an alicyclic structure. Such resin compositions gradually deteriorate in their excellent characteristics that alicyclic structure olefin resins such as cycloolefin random copolymers have as inherent properties when exposed to an environment at high temperature over a long period of time. The resin compositions also tend to be deteriorated when irradiated with such light having a short wavelength as an UV-ray, and show lowering of physical properties when exposed to sunlight in the open air over a long period.
Synthetic resins are often used for manufacturing optical instrument parts such as optical lenses, optical disc substrates and optical fibers in place of conventionally used glass.
It is desirable that optical instrument parts manufactured from such synthetic resins have high transparency, rigidity and impact resistance.
As the resins having such excellent properties, there have been conventionally used transparent resins such as polymethacrylate, polycarbonate and poly-4-methylpentene-1, but the present inventors have found that olefin resins having an alicyclic structure such as thermoplastic resins containing a random copolymer of chain olefin (e.g., ethylene) and cycloolefin are basically suitable for producing optical parts. For example, optical parts such as plastic lenses or substrates of optical discs can be produced by molding the above-mentioned random copolymer of chain olefin and cycloolefin through injection molding. Further, optical fibers can be produced by molding the random copolymer through extrusion molding. The optical instrument parts produced as mentioned above show high rigidity and high resistance to shocks in addition to the high transparency.
In the case of producing molded products having specific shapes by the above-mentioned molding method, the resin used therefor is desired to have a low viscosity, and the viscosity of the resin is generally made lower by raising a temperature of the resin. Especially when a molded product of small thickness is formed through injection molding, the resin is compelled to stay in the molding machine for a long period of time, and therefore the resin is also heated for a long period of time. Further, when the resin passes through a narrow part of a mold to produce a molded product of small thickness, a mechanical shearing force is applied to the resin, sometimes the molding resulting in local generation of heat in the resin.
On the other hand, in the case of producing filaments by extrusion molding, high speed spinning is desirably carried out from the viewpoint of increasing productivity, and for such a high speed spinning, it is desired to raise a temperature of the resin to lower the viscosity thereof. Further, when the high speed spinning is carried out, a mechanical shearing force is likely to be applied to the resin.
Owing to the above-mentioned external heating of the resin or generation of heat within the resin caused by the mechanical shearing force or the like, the resin is exposed to high temperatures for a long period of time during molding, and thereby the resin is apt to be thermally decomposed or thermally deteriorated during molding. As a result, the resulting molded product is colored and reduces its transparency.
For preventing the thermal decomposition or thermal deterioration of the resin during molding, a heat-resistant stabilizer is generally incorporated into the resin. This method is effective for the production of known resin molded products. The resin can be prevented from thermal decomposition or thermal deterioration occurring during molding by using this method, and consequently the obtained molded product can be also prevented from coloring or lowering of the transparency required to a satisfactory degree for conventional resin molded products.
However, in the field such as the optical one where very high transparency is required for the parts, transparency of molded products becomes a very important factor. Accordingly even when the above-mentioned conventional method is employed for preventing thermal decomposition or thermal deterioration of the resin, the resulting molded product tends to be colored because of slight burning of the resin taking place in the heating stage. Further, the stabilizer contained in the resin becomes per sea colored oxide, and the colored oxide also colors the resulting molded product, that is, the final optical part reduces its transparency. Moreover, the thermal decomposition or the thermal deterioration of the resin during molding sometimes brings about extremely small-sized voids within the resulting molded product, and hence optical instrument parts having excellent optical properties cannot be produced.
The present inventors have also found that since a random copolymer of chain olefin and cycloolefin has an alicyclic structure portion in its molecule, conjugated double bonds are easily formed by the thermal decomposition or the like in this portion, and that the random copolymer having such features is more easily colored as compared with general polyolefins. In addition, formation of such conjugated double bonds lowers a transmittance of light in the short wavelength region, resulting in lowering the optical properties in the visible region of the random copolymer and restricting the use of the final optical parts.
The present inventors have made various proposals with respect to additives capable of preventing thermal decomposition or thermal deterioration in such resin molded products requiring high transparency as optical instrument parts.
For example, there are
an optical transparent substrate produced by adding two or more kinds of phenolic oxides having a .beta.-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl group to a transparent thermoplastic resin, as described in Japanese Patent L-O-P No. 14101/1988; PA1 an optical transparent substrate produced by adding .beta.-(3,5-di-tert-butyl-4-hydroxyphenyl)alkylpropionate in which the alkyl group forming an ester part has up to 10 carbon atoms to a transparent thermoplastic resin, as described in Japanese Patent L-O-P No. 15201/1988; PA1 an optical transparent substrate produced by adding a phenolic antioxidant having a cycloalkyl group to a transparent thermoplastic resin, as described in Japanese Patent L-O-P No. 23101/1988; and PA1 an optical disc having a substrate produced by adding a phenolic antioxidant and an ester of an aliphatic acid with a polyol in which a portion of hydroxyl groups of a tri- or more-valent polyol is esterified to a thermoplastic resin, as described in Japanese Patent L-O-P No. 110630/1988. PA1 bicyclo [2,2,1]hept-2-ene derivatives, PA1 tetracyclo[4,4,0,1.sup.2.5,1.sup.7.10 ]3-dodecene derivatives; PA1 octacyclo[8,8,0,1.sup.2.9 1.sup.4.7,1.sup.11.18, 1.sup.13.16, 0.sup.3.8,0.sup.12.17 ]-5-docosene derivatives; PA1 pentacyclo[6,6,1,1.sup.3.6,0.sup.2.7,0.sup.9.14 ]-4-hexadecene derivatives; PA1 heptacyclo-5-icosene derivatives; PA1 heptacyclo-5-heneicosene derivatives; PA1 tricyclo[4,3,0,1.sup.2.5 ]-3-decene derivatives; PA1 tricyclo[4,3,0,1.sup.2.5 ]-3-undecene derivatives; PA1 pentacyclo[6,5,1,1.sup.3.6,0.sup.2.7,0.sup.9.13 ]-4-pentadecene derivatives; PA1 pentacyclopentadecadiene derivatives; PA1 pentacylo[4,7,0,1.sup.2.5,0.sup.8.13,1.sup.9.12 ]-3-pentadecene derivatives; PA1 pentacyclo[7,8,0,1.sup.3.6,0.sup.2.7,1.sup.10.17,0.sup.11.16 1.sup.12.15 ]-4-eicosene derivatives; and PA1 nonacyclo[9,10,1,1,4,7,0.sup.3.8,0.sup.2.10,0.sup.12.21,1.sup.13.20,0.sup.1 4.19,1.sup.15.1.sup.8 ]-5-pentacosene derivatives. PA1 .alpha.-olefins having from 3 to 20 carbon atoms such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene; PA1 cycloolefins such as cyclopentene, cyclohexene, 3-methylcyclohexene, cyclooctene and 3a, 5, 6, 7a-tetrahydro-4, 7-methano-1H-indene; PA1 non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene; and PA1 norbornene compounds such as norbornene-2, 5-methylnorbornene-2, 5-ethylnorbornene-2, 5-isopropylnorbornene-2, 5-n-butylnorbornene-2, 5-iso-butylnorbornene-2, 5,6-dimethylnorbornene-2, 5-chloronorbornene-2, 2-fluoronorbornene-2 and 5,6-dichloronorbornene-2. PA1 VO(OR).sub.a X.sub.b or PA1 V(OR) .sub.c X.sub.d wherein R is a hydrocarbon group, X is halogen, and a, b, c and d are numbers satisfying 0&lt;a&lt;3, 0&lt;b&lt;3, 2&lt;a+b&lt;3, 0&lt;c&lt;4, 0&lt;d&lt;4, and 3&lt;c+d&lt;4. PA1 oxygen-containing electron donors such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic and inorganic acids, ethers, acid amides, acid anhydrides and alkoxysilanes; and PA1 nitrogen-containing electron donors such as ammonia, amines, nitriles and isocyanates. PA1 alcohols having from 1 to 18 carbon atoms, such as methanol, ethanol, propanol, pentanol, hexanol, octanol, dodecanol,octadecyl alcohol, oleyl alcohol, benzyl alcohol, phenylethyl alcohol, isopropyl alcohol, cumyl alcohol and isopropylbenzyl alcohol; PA1 phenolic compounds having from 6 to 20 carbon atoms, which may have a lower alkyl group, such as phenol, cresol, xylenol, ethylphenol, propylphenol, nonylphenol, cumylphenol and naphthol; PA1 ketones having from 3 to 15 carbon atoms, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone and benzoquinone; PA1 aldehydes having from 2 to 15 carbon atoms, such as acetaldehyde, propionaldehyde, octylaldehyde, benzaldehyde, tolualdehyde and naphthoaldehyde; PA1 organic acid esters having from2 to 30 carbon atoms, such as methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octal acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, methyl chloroacetate, ethyl dichloroacetate, methyl (meth)acrylate, ethyl crotonate, ethyl cyclohexanecarboxylate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, methyl toluylate, ethyl toluylate, amyl toluylate, ethyl ethylbenzoate, methyl anisate, n-butyl maleate, diisobutyl methylmalonate, di-n-hexyl cyclohexenecarboxylate, diethyl nadate, diisopropyl tetrahydrophthalate, diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, di-2-ethylhexyl phthalate, .gamma.-butyrolactone, .delta.-valerolactone, coumarin, phthalide and ethylene carbonate; PA1 acid halides having from 2 to 15 carbon atoms, such as acetyl chloride, benzoyl chloride, toluyl chloride and anisic acid chloride; PA1 ethers having from 2 to 20 carbon atoms, such as methyl ether, ethyl ether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, anisole and diphenyl ether; PA1 acid amides such as acetamide, benzamide and toluamide; PA1 amines such as methylamine, ethylamine, diethylamine, tributylamine, piperidine, tribenzylamine, aniline, pyridine, picoline and tetramethylenediamine; PA1 nitriles such as acetonitrile, benzonitrile and tolunitrile; and PA1 alkoxysilanes such as ethyl silicate and diphenyldimethoxysilane. The illustrated electron donors may be used alone or in combination. PA1 compounds having the formula of R.sup.1.sub.m Al(OR.sup.2).sub.3--m wherein R.sup.1 and R.sup.2 are as defined above, and m is a number preferably satisfying 1.5&lt;m 21 3; PA1 compounds having the formula of R.sup.1.sub.m AlX.sub.3-m wherein R.sup.1 and X are as defined above, and m is a number preferably satisfying 0&lt;m&lt;3; PA1 compounds having the formula of R.sup.1.sub.m AlH.sub.3-m wherein R.sup.1 is as defined above, and m is a number preferably satisfying 2&lt;m&lt;3; and PA1 compounds having the formula of R.sup.1.sub.m Al(OR.sup.2).sub.n X.sub.q wherein R.sup.1, R.sup.2 and X are as defined above, and m, n and q are numbers satisfying 0&lt;m&lt;3, 0&lt;n&lt;3, 0&lt;q&lt;3 and m+n+q=3. PA1 trialkylaluminum compounds such as triethylaluminum, tributylaluminum and triisopropylaluminum; PA1 dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide; PA1 alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide; PA1 partially alkoxylated alkylaluminum compounds such as those having an average composition represented by, for example, the formula of R.sup.1.sub.2.5 Al(OR.sup.2).sub.0.5 ; PA1 dialkylaluminum halides such as diethylaluminum chloride, dibutylaluminum chloride and diethylaluminum bromide; PA1 alkylaluminum sesquihalides such as ethylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; PA1 partially halogenated alkylaluminum compounds such as ethylaluminum dichloride, propylaluminum dichloride and butylaluminum dibromide; PA1 dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride; PA1 partially hydrogenated alkylaluminum compounds such as ethylaluminum dihydride and propylaluminum dihydride (alkylaluminum dihydride); and PA1 partially alkoxylated and halogenated alkylaluminum compounds such as ethylaluminum ethoxychloride, butylaluminum butoxychloride and ethylaluminum ethoxybromide. PA1 (C.sub.2 H.sub.5).sub.2 AlOAl(C.sub.2 H.sub.5).sub.2, PA1 (C.sub.4 H.sub.9).sub.2 AlOAl(C.sub.4 H.sub.9).sub.2, and PA1 (C.sub.2 H.sub.5).sub.2 AlNAl(C.sub.2 H.sub.5).sub.2. PA1 C.sub.6 H.sub.5 PA1 LiAl(C.sub.2 H.sub.5).sub.4, and PA1 LiAl(C.sub.7 H.sub.15).sub.4. PA1 (i) a flexible polymer having repeating units derived from a cycloolefin; PA1 (ii) an .alpha.-olefin copolymer; PA1 (iii) an .alpha.-olefin/diene copolymer; PA1 (iv) an aromatic vinyl hydrocarbon/conjugated diene flexible copolymer; and PA1 (v) a flexible polymer or copolymer prepared from isobutylene, or isobutylene and conjugated diene. PA1 organic peroxides or organic peresters such as benzoyloxy peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxide benzoate) hexene-3, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di(tert-gutylperoxy)hexene-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)haxane, tert-butyl perbenzoate, tert-butyl per-sec-octate, tert-butyl perpivalate, cumyl perpivalate and tert-butyl perdiethylacetate; and PA1 azo compounds such as azobisisobutyronitrile and dimethylazoisobutyrate. Of these compounds, there can be preferably used dialkyl peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexene-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,4-bis(tert-butylperoxyisopropyl)benzene. PA1 ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; PA1 peroxy ketals such as 1,1-bis(tert-butylperoxy)cyclohexane and 2,2-bis(tert-butylperoxy) octane; PA1 hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroxy peroxide and 1,1,3,3-tetramethylbutyl hydroperoxide; PA1 dialkyl peroxides such as di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane and 2,5-dimethyl-2,5-di(tert-butylperoxy) hexene-3; PA1 diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; and PA1 peroxy esters such as tert-butylperoxy acetate, tert-butylperoxy benzoate and 2,5-dimethyl-2,5-di(benzoylperoxy) hexane. PA1 glycerine tributylthiopropionate, glycerine trioctylthiopropionate, glycerine trilaurylthiopropionate and glycerine tristearylthiopropionate; PA1 trimethylolethane tributylthiopropionate, trimethylolethane trioctylthiopropionate, trimethylolethane trilaurylthiopropionate and trimethylolethane tristearylthiopropionate; and PA1 pentaerythritol tetrabutylthiopropionate, pentaerythritol tetraoctylthiopropionate, pentaerythritol tetralaurylthiopropionate and pentaerythritol tetrastearylthiopropionate. PA1 distearyl pentaerythritol diphosphite, PA1 di(nonylphenyl) pentaerythritol diphosphite, PA1 phenyl.4,4'-isopropylidenediphenol.pentaerythritol diphosphite, PA1 bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, PA1 bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, and PA1 phenyl bisphenol-A-pentaerythritol diphosphite. PA1 3,9-bis[2-{3-(3'-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dime thylethyl]-2,4,8, 10-tetraoxaspiro[5.5]undecane, PA1 3,9-bis[2-{3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionyloxy}-1,1-dimethy lethyl]-2,4,8,10tetraoxaspiro[5.5]undecane, and PA1 3,9-bis[2-{3-(3',5'-dimethyl-4-hydroxyphenyl)propionyloxy}-1,1,dimethylethy l]-2,4,8,10-tetraoxaspiro[5.5]undecane.
The above-mentioned phenolic antioxidants show high antioxidizing effects on polyolefins or random copolymers of chain olefin and cycloolefin, and consequently the substrates of optical discs produced by adding such antioxidants to the thermoplastic resin have high transparency.
Japanese Patent L-O-P No. 173226/1987 discloses that a transparent thermoplastic resin containing bis(dialkylphenyl) pentaerythritol diphosphite ester is molded to form a transparent substrate through injection molding.
However, optical instrument parts such as optical lenses and optical fibers need much higher transparency than the above-mentioned optical disc substrates, and therefore even when the phenolic antioxidants or antioxidizing techniques described in those publications are utilized, it has proved that there cannot be obtained optical lenses or optical fibers having much higher transparency.
As described above, the optical parts such as optical lenses and optical fibers requiring high transparency can be hardly produced even by incorporating known stabilizers into such olefin polymers having an alicyclic structure as random copolymers of chain olefins and cycloolefins.
Moreover, when such a catalyst containing chlorine atoms as Ziegler catalyst is employed for producing such olefin polymers having an alicyclic structure as random copolymers of chain olefins and cycloolefins, the catalyst containing chlorine atoms sometimes remains in the resulting copolymers. The remaining catalyst component decomposes to give a chlorine gas during molding, and the molding machine is likely to be corroded owing to the chlorine gas. When the molding machine is corroded, rust is easily introduced into the resin to color the resulting optical parts and to lower the transparency thereof.
The present invention intends to solve the above-mentioned problems with regard to prior art, and an object of the invention is to provide resin compositions having excellent thermal aging resistance and weathering resistance as well as excellent heat resistance, chemical resistance, dielectric characteristics, rigidity and dimension stability.
Another object of the invention is to provide resins which neither are colored, nor form fish-eyes, agglomerates of the resin and foams during forming molded resin products requiring transparency such as optical instruments parts and which are capable of giving resin molded products having high transparency.
A further object of the invention is to provide resin compositions capable of producing resin molded products without coloring, without forming fish-eyes, resin agglomerates and foams, and without lowering transparency, even when a thermoplastic resin obtained by using such a catalyst containing chlorine atoms as Ziegler catalyst is employed.
A still further object of the invention is to provide resin compositions having excellent thermal aging resistance and weathering resistance for industrial use other than optical use.